Blood flow in stented coronary artery: numerical fluid dynamics analysis

Recent generalization of stent implantation in interventional cardiology require full understanding of blood flow cartography. Interdepency between fluid stresses and in vivo cells covering lumen artery are regularly accused to be one of the instigator of neointimal proliferation (thickening of the inner layer of blood vessels) and mid-term restenosis. This study purpose to numericaly investigate the three dimensional flow in vicinity of an endoprothesis. We used a finite element method to simulate a steady flow of non-Newtonian fluid in a coronary artery using a rigid wall approximation. Results on the velocities, wall shear stress and wall shear stress gradients are presented. Theses simulations allow identification of stagnation site and low wall shear stress area that may be prone to clot formation and neointimal hyperplasia. Intra stent flow knowledge can potentially contribute to optimization of prothesis design and decreasing second intervention rate.

Determination of HbA1c concentrations in patients with acute myocardial infarction: comparison of the DCA 2000 device with the HPLC method

BACKGROUND

Recent studies suggest that HbA1c is an important predictor of the glycometabolic state of patients admitted for acute myocardial infarction (AMI).

OBJECTIVE

We aimed at comparing the results of HbA1c concentrations obtained by 2 different methods in patients with AMI.

RESEARCH DESIGN AND METHODS

In a first study, HbA1c was measured in all patients consecutively hospitalized for AMI, during a 6 month period using the HPLC method and the DCA 2000 device in the biochemistry laboratory. In a second study, HbA1c measured by the DCA 2000 device in the intensive care unit was compared with HbA1c determined by HPLC in the biochemistry laboratory in a similar sample of patients. In patients without personal history of diabetes, those patients with HbA1c > 6.5% (HPLC method), were classified as possible diabetes.

RESULTS

A total of 146 patients were included (119 males, 27 females; mean age: 63 +/- 15 years). Twenty-seven of the patients had a personal history of diabetes. HbA1c determined by 2 techniques were highly correlated (r = 0.939, P < 0.0001). The mean of the differences (Bland and Altman analysis) was 0.4 +/- 0.3%. Compared with the HPLC method, the sensitivity of DCA 2000 device for the detection of possible diabetes was 81.8 +/- 11.6 and the specificity was 99.1 +/- 0.9%. The diagnostic accuracy of DCA method was 97.5 +/- 1.4%. In the second study, the HbA1c concentrations of 21 additional subjects, determined in an intensive care unit, were not different from the first 21 patients of the first study.

CONCLUSIONS

HbA1c can be effectively determined using the DCA 2000 device. This method is reliable and easy to be implemented in an intensive care unit.

Prognostic value of admission plasma glucose and HbA in acute myocardial infarction

OBJECTIVE

Stress hyperglycaemia increases the risk of mortality after acute myocardial infarction in diabetic and in non-diabetic patients. We aimed to determine the contribution of admission plasma glucose and HbA(1c) on post-acute myocardial infarction prognosis.

PATIENTS AND METHODS

Admission plasma glucose and HbA(1c) were simultaneously measured in all patients consecutively hospitalized for acute myocardial infarction. Patient survival was measured on 5 and 28 days after admission. Patients were defined as having 'previously diagnosed diabetes' (personal history of diabetes defined using ADA 1997 criteria), 'no diabetes', those without previously diagnosed diabetes and HbA(1c) below 6.5%, or 'possible diabetes', i.e. those without previously diagnosed diabetes and HbA(1c) above 6.5%.

RESULTS

Of the 146 patients included, four had died by day 5 and 14 by day 28. Admission plasma glucose was higher in patients who had died by day 28 (11.7 +/- 5.8 vs. 8.0 +/- 3.3 mmol/l, P = 0.002), whereas HbA(1c) was not (6.4 +/- 1.9 vs. 6.1 +/- 0.8%, NS). Admission plasma glucose was significantly higher in those who had died by day 28 after adjustment on HbA(1c). A multivariate analysis, including sex, age and heart failure prior to acute myocardial infarction, showed that admission plasma glucose concentration was an independent predictor of survival after acute myocardial infarction. Twenty-seven of the patients had previously diagnosed diabetes and 119 had no history of diabetes. Eleven were found to have possible diabetes. Admission plasma glucose was significantly higher in previously diagnosed diabetes (11.1 +/- 5.6) than in the other groups: 7.7 +/- 2.9 in non-diabetes, 8.2 +/- 2.1 in possible diabetes (P < 0.0001). The relationship between HbA(1c)-adjusted admission plasma glucose and mortality after acute myocardial infarction was also found in the non-diabetes group.

CONCLUSIONS

Admission plasma glucose, even after adjustment on HbA(1c), is a prognostic factor associated with mortality after acute myocardial infarction. Acute rather than the chronic pre-existing glycometabolic state accounts for the prognosis after acute myocardial infarction.

Obstructive intramural coronary amyloidosis and papillary muscle rupture

Mitral papillary muscle rupture is usually caused by ischaemia as a complication of myocardial infarction. In a 76 year old patient with no significant disease or major cardiovascular risk factors, papillary muscle rupture was caused by obstructive intramural coronary amyloidosis, an unusual cause.

Resistance to aspirin in vitro at rest and during exercise in patients with angiographically proven coronary artery disease

BACKGROUND

Acetylsalicylic acid, or aspirin, is widely used in secondary prevention of coronary artery diseases, but the inhibition of platelet aggregation is not uniform in all individuals.

OBJECTIVE

To investigate the prevalence of aspirin resistance at rest and during exercise in coronary artery disease patients.

MATERIALS AND METHODS

Fifty patients with stable coronary artery disease were prospectively studied. All patients received aspirin (75-300 mg/day for >1 month) and no other antiplatelet therapy. Aspirin resistance was studied, at rest and immediately after a stress test, using the standardized platelet function analyzer (PFA-100(R), Dade-Behring). Aspirin resistance was defined as a normal collagen/epinephrine closure time (<186 s).

RESULTS

Ten patients (20%) were aspirin-resistant at rest. Out of the 40 patients who were aspirin-sensitive at rest, 9 (22%) were aspirin-resistant immediately after the exercise stress test. There were no differences in aspirin sensitivity regarding gender, age, diabetes, hypertension, dyslipidemia, platelet count, medical treatment or number of the coronary arteries involved.

CONCLUSIONS

Aspirin resistance is detected, at rest, in 20% of our patients with stable coronary artery disease. Aspirin treatment does not seem to protect against exercise-induced platelet activation in 22% of such patients, despite aspirin sensitivity at rest.

[Platelet polymorphism and coronary artery disease]

Several publications over the last ten years have addressed the problem of genetic mutation coding platelet membrane glycoproteins and thrombotic arterial disease. The principal polymorphisms studied are those of glycoproteins GPIIIa, GPIb and the GPIa-IIa complex. The relationships of each of these polymorphisms and myocardial infarction or coronary artery disease are reported and are often subject to controversy. The polymorphism PLA2 of the GPIIIa has been shown to be a risk factor for infarction in young people, especially when associated with cigarette smoking. Its role in triggering myocardial infarction or in the severity of coronary artery disease is not so clear in the general population. Two types of polymorphism concerning the GPIb and that of the GPIa-IIa complex should also predispose to early coronary thrombotic complications. In addition, the study of these platelet polymorphisms gives a better insight into individual sensitivity to platelet antiaggregant therapy.

[Doppler parameters in the followup of and evaluation of patients with heart failure]

Cardiac failure plays an increasing role in the daily practice of cardiologists and internists. Cardiac failure is purely diastolic in nearly 40% of cases. Whether purely diastolic or mixed, cardiac failure requires appropriate management in the long term. A step by step approach is often necessary and echocardiography with Doppler analysis of blood flow is certainly one of the most pertinent methods of following up these patients. In addition, new technologies now provide access to quantifiable regional left ventricular systolic and diastolic function: Doppler tissue and strain rate imaging will certainly be an additional help for the adaptation of strategies of management of cardiac failure in the near future.

[Systemic markers of inflammation after coronary angioplasty]

THE RISK OF RESTENOSIS: Coronary angioplasty is an effective treatment of stable and instable coronary disease and its principle limitation, despite technical progress, remains restenosis. In instable angina, the physiopathologic and prognostic role of inflammation proteins is well documented. THE ROLE OF THE C-REACTIVE PROTEIN (CRP): Is a validated risk factor for patients presenting with heart failure, whether instable or stable angina and in the general population. This risk factor is distinct from tobacco abuse, hypercholesterolemia or diabetes. In all the series studied to date, the frequency of restenosis following coronary angioplasty increases when CRP values are high prior to surgery and continue to rise up to the 48th or 72nd hour.

PERSPECTIVES

New therapeutic measures widen the possibilities of mechanical strategies (angioplasty with or without stent) and treatment of inflammatory mechanisms in the atheromatous plaques (statines, brachytherapy or "covered" stents).

[Cardiogenic shock due to myocardial infarction: surgical revascularization with centrifugal left ventricular assistance. Report of 2 cases treated successfully]

Cardiogenic shock in the acute phase of myocardial infarction still carries a high mortality. In young patients who cannot be revascularised by angioplasty, when medical therapy is failing, some workers recommend an energetic approach, even cardiac transplantation, often with the bridge of mechanical cardiac assistance. This is not possible everywhere, thus preventing possible myocardial salvage and resulting in fairly high mortality. The authors report two cases in which endoluminal revascularisation was not possible and so complete surgical revascularisation with left ventricular assistance was chosen. The two patients survived and one was successfully transplanted electively. This management may be proposed in young patients with multiple occlusions of large coronary arteries in post-infarction cardiogenic shock when medical management is failing despite intra-aortic balloon pumping.

Echocardiographic features of Candidaspecies endocarditis: 12 cases and a review of published reports

OBJECTIVE

To describe the specific echocardiographic features of Candidaspecies endocarditis.

DESIGN

Retrospective review of the case records of patients with confirmed candida endocarditis.

SETTING

Cases referred to three French university centres over an eight year period were studied.

DESIGN

12 patients with confirmedCandida species endocarditis infection were identified. The transthoracic (n = 12) and transoesophageal (n = 12) echocardiographic appearances were compared with the surgical findings (n = 10).

RESULTS

Large dense heterogeneous vegetations were found in 11/12 cases. A hyperechogenic heterogeneous myocardial texture, observed in seven of the 12 patients, was associated with extensive myocardial damage at surgery. While it was possible to diagnose candidal cardiac infection in all patients by transthoracic echocardiography, transoesophageal echocardiography was useful for optimal assessment of the valvar and paravalvar structures.

CONCLUSIONS

In the setting of endocarditis, the detection of myocardial involvement, which is characterised by a heterogeneous myocardial texture, is an argument in favour of Candida species endocarditis and may warrant early surgical intervention.

Echocardiographic features of Candida species endocarditis: 12 cases and a review of published reports

OBJECTIVE

To describe the specific echocardiographic features of Candida species endocarditis.

DESIGN

Retrospective review of the case records of patients with confirmed candida endocarditis.

SETTING

Cases referred to three French university centres over an eight year period were studied.

DESIGN

12 patients with confirmed Candida species endocarditis infection were identified. The transthoracic (n = 12) and transoesophageal (n = 12) echocardiographic appearances were compared with the surgical findings (n = 10).

RESULTS

Large dense heterogeneous vegetations were found in 11/12 cases. A hyperechogenic heterogeneous myocardial texture, observed in seven of the 12 patients, was associated with extensive myocardial damage at surgery. While it was possible to diagnose candidal cardiac infection in all patients by transthoracic echocardiography, transoesophageal echocardiography was useful for optimal assessment of the valvar and paravalvar structures.

CONCLUSIONS

In the setting of endocarditis, the detection of myocardial involvement, which is characterised by a heterogeneous myocardial texture, is an argument in favour of Candida species endocarditis and may warrant early surgical intervention.

Dobutamine stress echocardiography response of asymptomatic patients with diabetes

AIMS

This study investigated the role of dobutamine stress echocardiography for the silent diagnosis of myocardial ischemia in a diabetic population. Results from the stress test were compared between diabetic and nondiabetic groups.

METHODS

Forty-nine diabetics and 63 consecutive nondiabetics underwent dobutamine stress echocardiography between April and December 1999, to check for new regional wall-motion abnormalities. A single operator, using the same echograph with tissue harmonic imaging in each case, performed all the examinations, using the same techniques.

RESULTS

Significant coronary artery disease was detected in 9% of asymptomatic diabetics. Dynamic left ventricular obstruction was observed in 59% of the diabetic population and only 22% in the nondiabetic population. One patient suffered an adverse event (fast atrial fibrillation) during the stress test. Cardiac frequency at the beginning and end of the stress test differed significantly between the two populations.

CONCLUSION

Dobutamine stress echocardiography allows for detection of silent myocardial ischemia. In the diabetic population, we describe, for the first time under dobutamine infusion, a great number of dynamic left ventricular obstructions.

Normal coronary angiogram and dobutamine-induced left ventricular obstruction during stress echocardiography: a higher hemodynamic responsiveness to dobutamine

This study assessed the clinical or echographic factors predisposing to dynamic left ventricular obstruction (LVO) during dobutamine echocardiography (DE) in patients with angina-like chest pain but without coronary artery disease (CAD). DE is an effective technique for the noninvasive diagnosis of underlying CAD. During DE, an LVO is not unusual in ischemic patients.

METHODS

DE (5-40 microg/kg/min) was performed in 52 consecutive patients with angina-like chest pain and normal coronary angiogram. Mean (standard deviation) age was 61 +/- 10 years (27 men, 25 women). Dobutamine-induced LVO was defined as a new intracavitary flow acceleration of at least 3 msec in the left ventricle.

RESULTS

Dynamic LVO was observed during DE in 20 (38%) of the 52 patients and was not related to clinical or baseline echocardiographic parameters. The chronotropic response and the systolic blood pressure during DE were higher in the group with LVO (P < 0.03 and P < 0.05, respectively). Appearance of chest pain during the test was also more frequent when LVO occurred (P < 0.02).

CONCLUSION

Dynamic LVO is common during DE in a population of patients with angina-like chest pain without epicardial CAD and is associated with a higher hemodynamic responsiveness to dobutamine.

[First case of myocardial metastasis of an epidermoid tumor. Value of Doppler tissue imaging]

The authors report the first case of a poorly differentiated epidermoid oesophageal cancer with myocardial metastasis. The diagnosis of malignant invasion of the myocardium was made by transthoracic echocardiography with electrocardiographic changes of subepicardial ischaemia. The authors review the literature of metastasic cardiac disease after the study of this particular case and underline the value of Doppler tissue imaging for myocardial characterisation.

[Normal coronary angiography. Survival and functional status at 6 years]

Despite the development of non-invasive diagnostic techniques, the absence of significant coronary stenosis is observed in 10 to 30% of coronary angiographic studies. The authors report the survival and functional status at 6 years of 172 consecutive patients with symptoms of angina without significant angiographic coronary stenosis. The average age was 60.8 years with a sex ratio of 1.1 and chest pain as the indication for coronary angiography in over 90% of cases. The global mortality after an average of 75.6 months follow-up was 11%, lower in women (8.5%) than in men (13.3%) with an annual mortality of 16.3 per thousand. Sudden death was observed in 4 patients and a third of deaths was of cardiac origin. The persistence of symptoms was reported by 58% of patients, mainly atypical chest pain. Despite the result of coronary angiography, nearly half of the patients were followed up annually by a cardiologist, two thirds remained on anti-anginal therapy, 20% were treated by psychotropic agents and hospital admission to the cardiology department was required in 22% of cases during follow-up. None of the patients had myocardial infarction. Survival and myocardial function after normal coronary angiography therefore appear to be good in contrast with the functional status of these patients.

[Comparison of tissue harmonic imaging and standard imaging in echocardiography based on 4 different emission frequencies]

Harmonic imaging is an innovative technique which is now available in most of the echographic equipment currently on the market. The use of echographic contrast agents led to the introduction of this particular technology, which has largely superseded the former method. In everyday medical practice, it seems to provide a better definition of endocardial contours. In this article, the authors have described a prospective study including 32 patients with an average age of 64 years (+/- 5 years). The aim was to compare imaging quality obtained by 2 acquisition frequencies for standard imaging with that procured by harmonic imaging (emission and reception frequency, 2.5 and 3.3 MHz respectively for the former technique; emission and reception frequency, 1.7 and 2.2 MHz respectively for the latter). The overall scores given by 2 different examiners for emission and reception frequency were as follows: 3.28 and 3.15 for 2.5 MHz, 2.84 and 2.56 for 3.3 MHz regarding the standard technique; 2.56 and 3.031 for 1.7 MHz and 2.56 and 2.063 for 2.2 MHz for the harmonic imaging technique. The superior performance of tissue harmonic imaging has been confirmed in the endocardial study of the left ventricular segments and in the analysis of the mitral valve. This study shows that harmonic imaging, a technique which was easy to use in the present study, provides a means of obtaining an average level of ultrasound imaging that facilitates the interpretation of the clinical picture.

[Ultrasonic myocardial characterization. Application of an original method of acoustic quantification to analysis of healthy and hypertrophic interventricular septal myocardium]

Echocardiography does not provide objective tissue characterisation of sonified tissues. A recent advance has been the introduction of the radiofrequency signal. At present, its exploitation remains a research tool. The required material for quantification is still insufficiently robust and discriminative. The indices derived from histograms of grey scales are calculated by the majority of workers for regions of interest manually positioned in the image. This statistical method allows analysis of the average grey level but not of the architecture of the tissue examined. Tissue characterisation is, therefore, only a potential feature of echocardiography. The authors' approach consists in developing software applied to digital signal provided by the echograph and not directly by the transducer, as in the research based on the use of radiofrequency signals. This software allows characterisation of the texture by two statistical methods applied to signal processing: the histograms of the grey scales, the matrix of co-occurrence (assessing the make-up of the different grey scales in the region of interest). This tool of tissue characterisation is presented here in the studies of the interventricular septum in the parasternal long axis view. Two populations, one with healthy myocardium and the other with myocardial hypertrophy, have been studied. These two populations are differentiated in a significant manner by their respective values of parameters of myocardial texture characterisation in early diastole. Despite a number of methodological problems, this study confirms the hopes that it will be possible in the near future to obtain a quantitative "histological" definition of tissues by echocardiography.

[Tissue characterization by study of myocardial response to ultrasound. Review of the literature and perspectives]

Echocardiography is a routine daily cardiological investigation. Recent technological developments suggest that it may become possible to quantify myocardial texture and thereby achieve histological and functional definitions of cardiac diseases. Two approaches are under evaluation: "videodensitometry" uses tools of statistical quantification from the echocardiographic image; more recently, analysis of the radiofrequency signal has been proposed. This is based on direct exploitation of a continuous signal at the transducer head of wide dynamic range containing all the information received by the piezo-electric crystals. These two approaches have given encouraging preliminary results in the recognition of different myocardial hypertrophic reactions, in diabetic cardiac disease and in the identification of myocardial viability. Despite the many remaining problems, the perspectives are promising and a new field of echocardiography should see the light of day.

[Mycotic aneurysm of the splenic artery. A rare complication of surgically treated infectious endocarditis and its causative cardiac lesion]

The authors report the case of a 59 year old woman with mitral valve streptococcal endocarditis complicating rheumatic valvular disease with several metastatic septic complications. In addition to ocular and cerebral localisations, the patient developed a very rare mycotic aneurysm of the splenic artery. Mitral valve replacement was necessary because of severe mitral regurgitation with major dilatation of the left heart chambers. This surgery was performed under high dose heparin therapy. Large aneurysms of the splenic artery carry a high risk of rupture. This splenic artery aneurysm was treated in the same operative session as the valvular disease by a sternolaparotomy: the aneurysm was operated first of all, and then valvular replacement was performed. Three years later, the patient is well and cured of the endocarditis. To the authors' knowledge, this is the third report of mycotic aneurysm of the splenic artery and the first case combined with surgery of the infectious valvular disease and the gastro-intestinal artery aneurysm.

[Myocardial infarction caused by septic embolism during mitral endocarditis]

Embolic infarction is a rare complication of mitral valve endocarditis. The authors present the case of a patient with a linear vegetation of the anterior mitral leaflet measuring over 15 mm and entering the aortic valve orifice at each systole. This valvular infarction was the cause of an extensive anterior wall infarct treated by primary angioplasty because of haemodynamic instability. The outcome at 3 months was very favourable with regards to the mitral valve. However, a large mycotic coronary aneurysm developed at the site of angioplasty and there were sequellae of a large anterior wall infarction.

[Traumatic coronary dissection caused by deceleration. Report of a case]

Myocardial infarction is a rare complication of traumatic thoracic deceleration. The authors report the case of anterior myocardial infarction with dissection of the left anterior descending artery in a 16 year old boy who was injured in a motorbike accident without a penetrating thoracic wound. Therefore, the only pathological mechanism was deceleration. The authors review the 12 previously reported cases.

[The echocardiographic examination in adult cardiomyopathy]

Echocardiography allows distinction between the diastolic dysfunction of hypertrophic or restrictive cardiomyopathies and the systolic dysfunction of dilated cardiomyopathy. The diagnosis and prognosis may be deduced from echocardiographic parameters. In hypertrophic cardiomyopathy systolic function is normal and there is asymmetric left ventricular hypertrophy (> 13 mm) associated with a reduced diastolic dimension and atrial dilatation resulting from diastolic dysfunction. The prognosis could be related to the severity of left ventricular hypertrophy; right ventricular hypertrophy is uncommon and its severity seems to be related to that of left ventricular hypertrophy. Restrictive cardiomyopathies are less common and amyloidosis is the commonest cause. Symmetric hypertrophy with reduced diastolic dimensions is observed; right ventricular involvement occurs in about 30% of cases. The prognosis seems to be related to the degree of parietal infiltration and, at advanced stages, systolic function is abnormal (fractional shortening < 20% with a left ventricular diastolic dimension > or = 55 mm) and rapidly fatal. Dilated cardiomyopathy is diagnosed when wall thickness is normal but left ventricular diastolic dimensions > 27 mm/m2 and ejection fraction < 45%. Right and left ventricular dimensions of the same size, left ventricular diastolic dimensions > 70 mm and left ventricular ejection fractions < 20% are poor prognostic indicators.

[Contribution of doppler imaging of the myocardium to the study of cardiomyopathies]

Colour Doppler imaging (CDI) is a recent method of evaluation of cardiomyopathy based on intra-myocardial abnormalities. CDI provides quantitative assessment of myocardial wall motion both circumferential by studying the movements of the myocardium and longitudinal by studying the movements of the mitral annulus. The harmonious decrease in velocity between the endocardium and epicardium disappears in pathological conditions, showing disorganisation of wall motion within the myocardium. The decrease in the early diastolic transmural velocity gradient in patients with cardiomyopathy indicates diastolic dysfunction independent of the left ventricular systolic function. In addition, CDI is more sensitive than conventional Doppler echocardiography with grey scale because it enables earlier detection of changes induced by low-dose dobutamine, allowing distinction between trained athletes and patients with hypertrophic cardiomyopathy. The velocities of the mitral annulus help to prevent errors of interpretation of mitral blood flow as they are relatively independent on the left ventricular preload.

[Contribution of doppler echocardiography in the evaluation of ventricular filling in cardiac insufficiency and estimation of filling pressures]

The study of diastolic function is an essential step in Doppler echocardiographic investigation of cardiac failure. Although the recording of transmitral flow remains the basis of analysis of diastolic function, it should be completed by other Doppler parameters. In fact, the simple analysis of transmitral flow is not sufficient because of the interplay of other factors, especially the preload. The authors describe the complementary ultrasonographic approaches for analysis of diastolic function, especially the ventricular filling pressures, by recording of pulmonary venous flow, the kinetics of the mitral annulus and the propagation of intra-ventricular flow.

[Coronary angiography in octogenarians. Therapeutic impact and medium-term follow-up]

In the face of the general aging of the population and technical improvements, cardiologists are more commonly faced with the decision of whether to perform coronary angiography in octogenarians who are often in good general health. The morbidity and mortality of this investigation, its therapeutic impact and medium-term survival were analysed in 145 consecutive octogenarians who underwent coronary angiography between 1988 and 1996. In this study, coronary angiography was performed essentially for angina refractory to medical treatment and confirmed the severity of the lesions with stenosis of the left main stem in 7.6% of cases and multiple vessel disease in 67.5% of cases. The mortality related to the investigation was nil in this series. Revascularisation was feasible clinically and angiographically in 38% of cases (84% by angioplasty). The actuarial survival at 3 years was 65% in the group who underwent revascularisation and in the group treated medically.

[Candida albicans myocarditis or endocarditis? Echocardiographic aspects]

The authors report the case of a patient presenting with atypical features of Candida albicans cardiac infection, with unusual infectious destructive lesions. While the initial hypothesis was that of aortic endocarditis, the clinical course and operative findings showed echocardiographic features of septal micro-abscesses adjacent to the aortic orifice, which was devoid of any infectious lesions.

[3-dimensional reconstruction technic using power Doppler. In vitro use on normal and stenosed pulmonary artery bifurcations]

Power Doppler imaging is an ultrasonic technique representing circulating red cells as a colour signal independent of their direction and angle of analysis. This noninvasive technique provides a morphological representation of blood flow within a blood vessel. This in vitro study in pulsed flow enabled three-dimensional reconstruction of blood flow in the bifurcation of the pulmonary artery with automatic shifting of the ultrasound probe and an integral digital transfer of the echographic data. The software for treating the images and for volumic reconstruction of the flow is explained. This technique provides a quantitative method of assessing residual intrastenotic flow with a simple computer system.

[Physiopathology of myocardial infarction: the acute coronary occlusion]

Rupture of the atheromatous plaque, thrombosis and local vasoconstriction are involved in the genesis of acute myocardial infarction. The vulnerability of the plaque depends on its histological structure. Its fragility is related to the size of the lipid core, the thinness of the fibrous capsule and the inflammatory reaction. External aggression favourites rupture. This triggers both thrombogenesis by bringing the blood cells into contact with thrombogenic subendothelial factors and local vasoconstriction due to endothelial dysfunction. Although rupture of the plaque is an unpredictable event, there is a circadian variability the highest incidence of infarction being between 6 a.m. and midday. Comprehension of the physiopathology of myocardial infarction has opened up new therapeutic approaches which should reduce the incidence of plaque rupture. Prevention is based on stabilisation of the plaque by dietary hygiene, lipid-lowering drugs and, maybe, in the future, by local application of antisense oligonucleotides. Finally, anti-aggregant therapy (aspirin or anti-GIIb-IIIa) could prevent the formation or extension of the thrombus.

[Myocardial infarction by complete thrombosis of the left main coronary artery: emergency treatment with angioplasty with implantation of a coronary stent and follow-up at one year: a case report]

Acute occlusion of the left main coronary artery is usually responsible for cardiogenic shock, severe arrhythmias or sudden death. Despite the widespread use of emergency coronary angiography in acute myocardial infarction, occlusion of the left main coronary artery is rarely observed and its treatment remains controversial. The authors report the case of a young man with a previous history of radiotherapy for Hodgkin's disease, admitted for acute myocardial infarction due to complete thrombosis of the left main coronary artery treated as an emergency by percutaneous transluminal angioplasty and implantation of a Palmaz Schatz stent. There were no complications of the procedure and the patient was asymptomatic one year later.

[Papillary fibroelastoma. A rare etiology of strokes in young patients]

BACKGROUND

The papillary fibroelastomas are cardiac lesions, which typically occur on the cardiac valves, but rarely on the endocardium. The incidence of these benign primitive tumors varies from 0.002 to 0.33% and increases with advancing age.

METHODS

We report two cases of stroke, one in a 31-year-old man and the other in a 48-year-old woman, both admitted to the same stroke center.

RESULTS

The diagnostic studies were normal in these two patients, except for the echocardiography. The first showed an echogenic mass on the mitral valve on transthoracic echocardiography (TTE), confirmed by the transesophageal echocardiography (TEE). The second demonstrated a mass on the sigmoid aortic valve on TEE, but the TTE was normal. For these two patients, a surgical excision was carried out and pathologic examination concluded to a papillary fibroelastoma. After surgery, no recurrence was observed.

CONCLUSIONS

The papillary fibroelastomas are usually asymptomatic and easily detected by TEE. However, it can be revealed by stroke, myocardial infarction and lower limbs ischemia. These cardiac tumors should be surgically removed, since their complete excision remains the only means of avoiding a recurrence of embolism.

[Cardiac lymphoma disclosed by tamponade and complete atrioventricular block: apropos of a surgically treated case. Heart and lymphoma]

Cardiac lymphoma is becoming increasingly frequent, especially in the context of acquired immune deficiency syndrome, and due to progress in imaging, particularly echocardiography. The authors report the case of a 49-year-old patient in whom the diagnosis of cardiac lymphoma was established in the presence of complete atrioventricular block, tamponade and right atrial tumour. The authors review the various electrocardiographic and echocardiographic features of cardiac lymphoma.

[Reproducibility of measurements of blood gas exchange during exercise in mild cardiac failure: need for a preliminary test?]

The reproducibility of blood gas exchange measurements on exercise in chronic cardiac failure has already been established in patients familiar with this technique. The aim of this prospective study was to evaluate the reproducibility of cardiopulmonary parameters on exercise in a population of patients who had never undergone this type of investigation. Twenty patients with chronic cardiac failure in classes I to III of the NYHA classification, with a mean age of 55 +/- 11.5 years and a mean LV ejection fraction of 31.2 +/- 9%, underwent two cardiopulmonary exercise tests (CPX Medgraphic) performed on a bicycle ergometer. Patients underwent maximal exercise stress testing attaining 89% of the theoretical maximal heart rate and 1.14 of the respiratory quotient during the first test. There was no significant change in peak VO2 (22.5 ml/min/kg vs 22.6 ml/min/kg) or in ventilatory anaerobic threshold (12.8 ml/min/kg vs 12.7 ml/min/kg) between the two tests. The ventilatory anaerobic threshold could not be measured in one patient and seemed less reproducible than peak VO2 with a standard deviation of relative differences (T2-T1/T1) of 10.4 versus 7.8%. There was a significant increase in the duration of exercise (7.4 +/- 9.2%; p < 0.002) and a ventilatory flow (4.5 +/-, p = 0.03). This study shows that peak VO2 is a reproducible measurement in mild to moderate chronic cardiac failure, even in the absence of a preliminary test to familiarize the patient with the equipment. The reproducibility of the ventricular anaerobic threshold is less satisfactory than that of peak VO2. The increase in the duration of exercise is more dependent on motivation and should not be taken into account alone in the functional evaluation of chronic cardiac failure.

[Isolated left superior vena cava: value of intraoperative echocardiography for implantation of a cardiac pacemaker]

The authors report the case of a patient presenting with isolated left superior vena cava, for which intracardiac implantation of a cardiac pacemaker was facilitated by intraoperative transthoracic ultrasonographic detection of the course of the ventricular catheter. Transoesophageal ultrasonography confirmed the diagnosis and eliminated a possible associated malformation.